JP4470771B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention provides first fuel injection means (in-cylinder injector) for injecting fuel into the cylinder and second fuel injection means (intake passage injection) for injecting fuel into the intake passage or intake port. In particular, the present invention relates to a technique for correcting the amount of fuel injection from the first fuel injection means and the second fuel injection means.

  An injector for injecting intake passage for injecting fuel into the engine intake passage and an in-cylinder injector for injecting fuel at all times into the engine combustion chamber, the engine load being higher than a predetermined set load There is known an internal combustion engine that stops fuel injection from the intake passage injector when the engine load is low and injects fuel from the intake passage injector when the engine load is higher than the set load.

  Even in such an internal combustion engine, the fuel injection amount may not be a desired injection amount due to deposits accumulated in the injector and individual differences during manufacture. That is, the air-fuel ratio may deviate from a desired air-fuel ratio (for example, the theoretical air-fuel ratio). In order to correct the deviation of the fuel injection amount, the fuel injection amount is corrected by feedback control of the air-fuel ratio, similarly to the internal combustion engine in which one injector is provided for one cylinder.

  Japanese Patent Laying-Open No. 3-185242 (Patent Document 1) discloses a fuel injection amount control device for an internal combustion engine that accurately corrects the fuel injection amount in an internal combustion engine having a plurality of fuel injection valves per cylinder. This fuel injection amount control device learns a value based on an output signal from a control unit that controls fuel injection from a plurality of fuel injection valves according to an operating state and an oxygen sensor provided in an exhaust system of the engine. Each learning using a learning unit for correcting the fuel injection amount, a setting unit for setting a plurality of learning regions corresponding to the use states of the plurality of fuel injection valves, and each learning value learned in each of the learning regions And a correction unit that corrects the fuel injection amount in the operation state corresponding to the region.

According to the fuel injection amount control device described in this publication, the fuel injection valve that is used in the learning region matches the fuel injection valve that is used when the fuel injection amount is corrected using the learned value. Therefore, the correction accuracy of the fuel injection amount is improved. Accordingly, the air-fuel ratio followability is improved accordingly, and exhaust emission is improved. Further, since the error from the target air-fuel ratio becomes small, even if the air-fuel ratio is set to the lean side, the possibility of misfire can be reduced and fuel efficiency can be improved.
Japanese Patent Laid-Open No. 3-185242

  By the way, in an internal combustion engine, for example, at the time of cold start, the fuel injection amount is increased in order to improve startability and the like. When the fuel injection amount is increased in this way, the air-fuel ratio can inevitably change compared to the case where the fuel injection amount is not increased. However, in the fuel injection amount control device described in Japanese Patent Laid-Open No. 3-185242, the case where the fuel injection amount is increased is not taken into consideration. Therefore, there is a possibility that the fuel injection amount may be unnecessarily corrected by learning the learning value, and there may occur a case where the correction of the fuel injection amount based on the learning value is inappropriate.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a control device for an internal combustion engine that can appropriately correct the fuel injection amount.

  The control apparatus for an internal combustion engine according to the first invention includes a first fuel injection means for injecting fuel into the cylinder and a second fuel injection means for injecting fuel into the intake passage. Control the internal combustion engine. This control device injects fuel from only one of the first fuel injection means and the second fuel injection means at least during cranking and idling when the temperature of the internal combustion engine is equal to or lower than a predetermined value. As described above, the first control means for controlling the fuel injection means, and the second for controlling the fuel injection means so that the fuel is injected from the first fuel injection means and the second fuel injection means. Control means, a calculation means for calculating a correction value of the fuel injection amount based on the air-fuel ratio, and calculation of a correction value of the fuel injection amount at least during the period from the start of cranking of the internal combustion engine to the complete explosion And a permission means for permitting calculation of the correction value of the fuel injection amount in a predetermined period after the complete explosion of the internal combustion engine.

  According to the first invention, the first control means is one of the first fuel injection means and the second fuel injection means at least during cranking and idling when the temperature of the internal combustion engine is equal to or lower than a predetermined value. The fuel injection means is controlled so that the fuel is injected from only one of them. The second control means controls the fuel injection means so that fuel is injected from the first fuel injection means and the second fuel injection means. In an internal combustion engine in which the fuel injection means is controlled in this way, there are not always many opportunities for fuel to be injected from only one of the first fuel injection means and the second fuel injection means. Therefore, there are not always many opportunities to calculate the correction value of the fuel injection amount in the state where the fuel is injected from only one of the first fuel injection unit and the second fuel injection unit. Therefore, in a state where fuel is injected from only one of the first fuel injection unit and the second fuel injection unit, it is necessary to calculate a correction value for the fuel injection amount as much as possible. Therefore, the fuel can be injected from only one of the first fuel injection means and the second fuel injection means (cranking time and idling time when the temperature of the internal combustion engine is not more than a predetermined value can be included). It is conceivable to calculate the correction value even when the internal combustion engine is cold. By the way, when the internal combustion engine is started when it is cold, the fuel injection amount is transiently corrected (increased) at least during the period from the start of cranking to the complete explosion. Further, during a predetermined period after the complete explosion, the fuel injection amount is constantly corrected (increased) according to the temperature of the internal combustion engine. When the injection amount is increased transiently, the air-fuel ratio may change suddenly. On the other hand, when the injection amount is constantly increased, the air-fuel ratio is stabilized. Therefore, calculation of the fuel injection amount correction value is prohibited at least during the period from the start of cranking to the complete explosion. Calculation of the correction value of the fuel injection amount is permitted in a predetermined period after the complete explosion. Thereby, the correction value of the fuel injection amount can be calculated in a state where the air-fuel ratio is stable. Therefore, erroneous calculation of the correction value can be suppressed. As a result, it is possible to provide a control device for an internal combustion engine that can appropriately correct the fuel injection amount.

  In the control device for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the first control means is configured to perform the cranking and idling when the temperature of the internal combustion engine is equal to or lower than a predetermined value. Means for controlling the fuel injection means are included so that fuel is injected only from the second fuel injection means.

  According to the second invention, the fuel injection means is controlled so that the fuel is injected only from the second fuel injection means at the time of cranking and idling when the temperature of the internal combustion engine is not more than a predetermined value. . In the internal combustion engine in which the fuel injection means is controlled in this way, there are not always many opportunities for fuel to be injected only from the second fuel injection means. Therefore, there are not always many opportunities to calculate the correction value of the fuel injection amount in the state where the fuel is injected only from the second fuel injection means. Therefore, in a state where fuel is injected only from the second fuel injection means, it is necessary to calculate a correction value for the fuel injection amount as much as possible. Therefore, the correction value can be set even when the internal combustion engine is cold, in which fuel can be injected only from the second fuel injection means (the temperature of the internal combustion engine can be cranking or idling when the temperature is lower than a predetermined value). It is conceivable to calculate. By the way, when the internal combustion engine is started when it is cold, the fuel injection amount is transiently corrected (increased) at least during the period from the start of cranking to the complete explosion. Further, during a predetermined period after the complete explosion, the fuel injection amount is constantly corrected (increased) according to the temperature of the internal combustion engine. When the injection amount is increased transiently, the air-fuel ratio may change suddenly. On the other hand, when the injection amount is constantly increased, the air-fuel ratio is stabilized. Therefore, calculation of the fuel injection amount correction value is prohibited at least during the period from the start of cranking to the complete explosion. Calculation of the correction value of the fuel injection amount is permitted in a predetermined period after the complete explosion. Thereby, the correction value of the fuel injection amount can be calculated in a state where the air-fuel ratio is stable. Therefore, erroneous calculation of the correction value can be suppressed.

  In the control apparatus for an internal combustion engine according to the third invention, in addition to the configuration of the first or second invention, the predetermined period is a period in which the fuel injection amount is corrected based on the temperature of the internal combustion engine.

  According to the third invention, the air-fuel ratio is stabilized when the fuel injection amount is constantly corrected in accordance with the temperature of the internal combustion engine. During such a period, calculation of the fuel injection amount correction value is permitted. Thereby, the correction value of the fuel injection amount can be calculated in a state where the air-fuel ratio is stable. Therefore, erroneous calculation of the correction value can be suppressed.

  The control apparatus for an internal combustion engine according to a fourth aspect of the invention includes a fuel based on a correction value calculated when the fuel injection amount is corrected on the basis of other than the temperature and air-fuel ratio of the internal combustion engine in addition to the configuration of the third aspect of the invention. Means for prohibiting correction of the injection amount is further included.

  According to the fourth aspect of the invention, the correction calculated when the fuel injection amount is corrected based on other than the temperature and air-fuel ratio of the internal combustion engine (for example, fuel adhering to the wall surface of the intake port or fuel purged from the canister). Correction of the fuel injection amount based on the value is prohibited. As a result, the fuel injection amount is unnecessarily corrected by the correction value calculated when the fuel injection amount is transiently corrected based on the fuel adhering to the wall surface of the intake port or the fuel purged from the canister. Can be suppressed. Therefore, the fuel injection amount can be corrected appropriately.

  In the control apparatus for an internal combustion engine according to the fifth invention, in addition to the configuration of any one of the first to fourth inventions, the first fuel injection means is an in-cylinder injector. The second fuel injection means is an intake passage injector.

  According to the fifth aspect of the present invention, in the internal combustion engine that shares the injected fuel by separately providing the in-cylinder injector that is the first fuel injection means and the intake passage injection injector that is the second fuel injection means, It is possible to correct the fuel injection amount.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
FIG. 1 shows a schematic configuration diagram of an engine system controlled by an engine ECU (Electronic Control Unit) which is a control device for an internal combustion engine according to a first embodiment of the present invention. Although FIG. 1 shows an in-line four-cylinder gasoline engine as an engine, the present invention is not limited to such an engine, and various types of engines such as a V-type 6-cylinder engine and a V-type 8-cylinder engine can be used. Applicable to engine.

  As shown in FIG. 1, the engine 10 includes four cylinders 112, and each cylinder 112 is connected to a common surge tank 30 via a corresponding intake manifold 20. The surge tank 30 is connected to an air cleaner 50 via an intake duct 40, an air flow meter 42 is disposed in the intake duct 40, and a throttle valve 70 driven by an electric motor 60 is disposed. The opening degree of throttle valve 70 is controlled based on the output signal of engine ECU 300 independently of accelerator pedal 100. On the other hand, each cylinder 112 is connected to a common exhaust manifold 80, and this exhaust manifold 80 is connected to a three-way catalytic converter 90.

  For each cylinder 112, an in-cylinder injector 110 for injecting fuel into the cylinder, and an intake passage injection injector 120 for injecting fuel into the intake port or / and the intake passage. And are provided respectively. These injectors 110 and 120 are controlled based on the output signal of engine ECU 300, respectively. The in-cylinder injectors 110 are connected to a common fuel distribution pipe 130, and this fuel distribution pipe 130 is connected to the fuel distribution pipe 130 through a check valve 140, and is driven by an engine. A high-pressure fuel pump 150 is connected. In the present embodiment, an internal combustion engine in which two injectors are separately provided will be described, but the present invention is not limited to such an internal combustion engine. For example, it may be an internal combustion engine having one injector that has both an in-cylinder injection function and an intake passage injection function.

  As shown in FIG. 1, the discharge side of the high-pressure fuel pump 150 is connected to the suction side of the high-pressure fuel pump 150 via an electromagnetic spill valve 152. When the amount of fuel supplied from the pump 150 into the fuel distribution pipe 130 is increased and the electromagnetic spill valve 152 is fully opened, the fuel supply from the high pressure fuel pump 150 to the fuel distribution pipe 130 is stopped. ing. Electromagnetic spill valve 152 is controlled based on the output signal of engine ECU 300.

  On the other hand, each intake passage injector 120 is connected to a common low-pressure fuel distribution pipe 160, and the fuel distribution pipe 160 and the high-pressure fuel pump 150 are connected to a common fuel pressure regulator 170 through an electric motor drive type. The low-pressure fuel pump 180 is connected. Further, the low pressure fuel pump 180 is connected to the fuel tank 200 via a fuel filter 190. The fuel pressure regulator 170 returns a part of the fuel discharged from the low-pressure fuel pump 180 to the fuel tank 200 when the fuel pressure of the fuel discharged from the low-pressure fuel pump 180 becomes higher than a predetermined set fuel pressure. Accordingly, the fuel pressure supplied to the intake manifold injector 120 and the fuel pressure supplied to the high-pressure fuel pump 150 are prevented from becoming higher than the set fuel pressure.

  The engine ECU 300 is composed of a digital computer, and is connected to each other via a bidirectional bus 310, a ROM (Read Only Memory) 320, a RAM (Random Access Memory) 330, a CPU (Central Processing Unit) 340, and an input port 350. And an output port 360.

  The air flow meter 42 generates an output voltage proportional to the amount of intake air, and the output voltage of the air flow meter 42 is input to the input port 350 via the A / D converter 370. A water temperature sensor 380 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine 10, and the output voltage of the water temperature sensor 380 is input to the input port 350 via the A / D converter 390.

  A fuel pressure sensor 400 that generates an output voltage proportional to the fuel pressure in the fuel distribution pipe 130 is attached to the fuel distribution pipe 130, and the output voltage of the fuel pressure sensor 400 is input via the A / D converter 410. Input to port 350. The exhaust manifold 80 upstream of the three-way catalytic converter 90 is provided with an air-fuel ratio sensor 420 that generates an output voltage proportional to the oxygen concentration in the exhaust gas. The output voltage of the air-fuel ratio sensor 420 is converted into an A / D converter. It is input to the input port 350 via 430.

The air-fuel ratio sensor 420 in the engine system according to the present embodiment is a global air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned by the engine 10. The air-fuel ratio sensor 420 may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture burned in the engine 10 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  In the present embodiment, engine ECU 300 calculates a feedback correction amount for the total fuel injection amount based on the output voltage of air-fuel ratio sensor 420. Further, when a predetermined learning condition is satisfied, a learning value of the feedback correction amount (a value representing a constant deviation amount of the fuel injection amount) is calculated. The calculation of the feedback correction amount and its learning value is performed within a predetermined learning region with the intake air amount as a parameter. The learning area will be described in detail later.

  The feedback correction amount and the method for calculating the learning value thereof may be a technique generally used in an internal combustion engine provided with one injector per cylinder, and will be described in detail here. Will not repeat.

  The accelerator pedal 100 is connected to an accelerator opening sensor 440 that generates an output voltage proportional to the depression amount of the accelerator pedal 100, and the output voltage of the accelerator opening sensor 440 is input to the input port 350 via the A / D converter 450. Is input. The input port 350 is connected to a rotational speed sensor 460 that generates an output pulse representing the engine rotational speed. In the ROM 320 of the engine ECU 300, the value of the fuel injection amount and the engine cooling that are set according to the operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 440 and the engine speed sensor 460 described above are stored. Correction values based on the water temperature and the like are previously mapped and stored.

  Referring to FIGS. 2 and 3, the injection ratio of in-cylinder injector 110 and intake manifold injector 120 (hereinafter referred to as DI ratio (r)), which is information corresponding to the operating state of engine 10, is also referred to. Will be described). These maps are stored in the ROM 320 of the engine ECU 300. FIG. 2 is a map for the warm of the engine 10, and FIG. 3 is a map for the cold of the engine 10.

  As shown in FIG. 2 and FIG. 3, these maps are expressed in percentages where the engine 10 rotational speed is on the horizontal axis, the load factor is on the vertical axis, and the share ratio of the in-cylinder injector 110 is the DI ratio r. It is shown.

  As shown in FIGS. 2 and 3, the DI ratio r is set for each operation region determined by the rotation speed and load factor of the engine 10. “DI ratio r = 100%” means a region where fuel injection is performed only from in-cylinder injector 110, and “DI ratio r = 0%” means from intake manifold injector 120. This means that only the region where fuel injection is performed. “DI ratio r ≠ 0%”, “DI ratio r ≠ 100%” and “0% <DI ratio r <100%” indicate that in-cylinder injector 110 and intake passage injector 120 perform fuel injection. It means that the area is shared. In general, the in-cylinder injector 110 contributes to an increase in output performance, and the intake manifold injector 120 contributes to the uniformity of the air-fuel mixture. By using two types of injectors having different characteristics depending on the rotation speed and load factor of the engine 10, the engine 10 is in a normal operation state (for example, when the catalyst is warmed up at idle when the engine 10 is in an abnormal state other than the normal operation state). In this case, only homogeneous combustion is performed.

  Further, as shown in FIG. 2 and FIG. 3, the DI share ratio r of the in-cylinder injector 110 and the intake manifold injector 120 is defined by dividing it into a warm map and a cold map. did. If the temperature of the engine 10 is different, the temperature of the engine 10 is detected by detecting the temperature of the engine 10 using a map set so that the control areas of the in-cylinder injector 110 and the intake manifold injector 120 are different. If it is equal to or higher than a predetermined temperature threshold value, the warm time map shown in FIG. 2 is selected. Otherwise, the cold time map shown in FIG. 3 is selected. Based on the selected maps, the in-cylinder injector 110 and / or the intake manifold injector 120 are controlled based on the rotation speed and load factor of the engine 10.

  In the present embodiment, the fuel injection amount from in-cylinder injector 110 and the fuel from intake manifold injector 120 are based on DI ratio r so that the total fuel injection amount becomes a desired injection amount. The injection amount is determined.

  The engine speed and load factor of engine 10 set in FIGS. 2 and 3 will be described. In FIG. 2, NE (1) is set to 2500 to 2700 rpm, KL (1) is set to 30 to 50%, and KL (2) is set to 60 to 90%. Further, NE (3) in FIG. 3 is set to 2900-3100 rpm. That is, NE (1) <NE (3). In addition, NE (2) in FIG. 2 and KL (3) and KL (4) in FIG. 3 are also set as appropriate.

  When FIG. 2 and FIG. 3 are compared, NE (3) of the map for cold shown in FIG. 3 is higher than NE (1) of the map for warm shown in FIG. This indicates that as the temperature of the engine 10 is lower, the control range of the intake manifold injector 120 is expanded to a higher engine speed range. That is, since the engine 10 is in a cold state, deposits are unlikely to accumulate at the injection port of the in-cylinder injector 110 (even if fuel is not injected from the in-cylinder injector 110). For this reason, it sets so that the area | region which injects a fuel using the intake manifold injector 120 may be expanded, and a homogeneity can be improved.

  Comparing FIG. 2 and FIG. 3, in the region where the engine 10 has a rotational speed of NE (1) or higher in the warm map and in the region of NE (3) or higher in the cold map, “DI ratio r = 100% ". Further, the load factor is “DI ratio r = 100%” in the region of KL (2) or higher in the warm map and in the region of KL (4) or higher in the cold map. This indicates that only the in-cylinder injector 110 is used in a predetermined high engine speed region, and only the in-cylinder injector 110 is used in a predetermined high engine load region. . That is, in the high speed region and the high load region, even if the fuel is injected only by the in-cylinder injector 110, the engine 10 has a high rotational speed and load, and the intake amount is large. It is because it is easy to homogenize. Thus, the fuel injected from the in-cylinder injector 110 is vaporized with latent heat of vaporization (sucking heat from the combustion chamber) in the combustion chamber. Thereby, the temperature of the air-fuel mixture at the compression end is lowered. As a result, the knocking performance is improved. Further, since the temperature of the combustion chamber is lowered, the suction efficiency is improved and high output can be expected.

  In the warm map shown in FIG. 2, only the in-cylinder injector 110 is used below the load factor KL (1). This indicates that when the temperature of the engine 10 is high, only the in-cylinder injector 110 is used in a predetermined low load region. This is because when the engine 10 is warm, the engine 10 is in a warm state, and deposits are likely to accumulate at the injection port of the in-cylinder injector 110. However, since the injection port temperature can be lowered by injecting fuel using the in-cylinder injector 110, it is conceivable to avoid deposit accumulation, and the minimum fuel injection amount of the in-cylinder injector Therefore, it is conceivable that the in-cylinder injector 110 is not blocked, and for this reason, the in-cylinder injector 110 is used as an area.

  Comparing FIG. 2 and FIG. 3, the region of “DI ratio r = 0%” exists only in the cold map of FIG. 3. This indicates that when the temperature of the engine 10 is low, only the intake manifold injector 120 is used in a predetermined low load region (KL (3) or less). This is because the engine 10 is cold and the load on the engine 10 is low and the intake air amount is low, so that the fuel is difficult to atomize. In such a region, it is difficult to perform good combustion with the fuel injection by the in-cylinder injector 110. In particular, a high output using the in-cylinder injector 110 is required in the region of low load and low rotation speed. Therefore, only the intake passage injector 120 is used without using the in-cylinder injector 110.

  In addition, in the case other than the normal operation, the in-cylinder injector 110 is controlled so as to perform stratified combustion when the engine 10 is at the time of catalyst warm-up when idling (in a non-normal operation state). By performing stratified charge combustion only during such catalyst warm-up operation, catalyst warm-up is promoted and exhaust emission is improved.

  Furthermore, in the present embodiment, separately from the cold map shown in FIG. 3, when the engine 10 is cold started (when the temperature of the cooling water of the internal combustion engine is lower than a predetermined temperature). “DI ratio r = 0%”, that is, fuel is injected only from the intake manifold injector 120. Therefore, at the time of cranking in a state where the temperature of the cooling water of the internal combustion engine is lower than a predetermined temperature, fuel is injected only from the intake manifold injector 120. Further, when the engine 10 is cold idle (when idling when the temperature of the cooling water of the internal combustion engine is lower than a predetermined temperature), fuel is injected only from the intake manifold injector 120. Instead of injecting fuel only from the intake manifold injector 120, fuel may be injected only from the in-cylinder injector 110.

  With reference to FIG. 4 and FIG. 5, the learning region in which the feedback correction amount and its learning value are calculated will be described. FIG. 4 shows a learning region in the warm map, and FIG. 5 shows a learning region in the cold map.

  In FIG. 4 and FIG. 5, a region sandwiched by curves indicated by alternate long and short dashed lines is a learning region. The learning area is divided according to the intake air amount. The reason why the learning area is set according to the intake air amount is that the error in the output of the air flow meter 42 differs depending on the intake air amount.

  In the present embodiment, four learning areas from learning areas (1) to (4) are provided. The intake air amount increases in the order of the learning area (1), the learning area (2), the learning area (3), and the learning area (4). Note that the number of learning regions is not limited to four.

  In the present embodiment, in addition to the learning area, the injection area ("DI ratio r = 100%" area, "0% <DI ratio r <100%" area, and "DI ratio r = 0%" area) ), The feedback correction amount and its learning value are calculated. That is, for each injection region, the feedback correction amount and its learning value are calculated for each learning region.

  With reference to FIG. 6, a control structure of a program executed by engine ECU 300 which is the control device for the internal combustion engine according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, engine ECU 300 determines whether a start request for engine 10 has been detected or not. For example, when the start switch is turned on, or when the ignition key is operated to the start position, it is determined that a start request for the engine 10 is detected. If a start request is detected (YES in S100), the process proceeds to S102. If not (NO in S100), the process returns to S100. In S102, engine ECU 300 starts engine 10 by transiently increasing the fuel injection amount and cranking engine 10.

  In S104, engine ECU 300 detects cooling water temperature TW of engine 10 based on the signal transmitted from water temperature sensor 380. In S106, engine ECU 300 determines whether or not cooling water temperature TW is lower than threshold value TW (0). If cooling water temperature TW is lower than threshold value TW (0) (YES in S106), the process proceeds to S108. If not (NO in S106), this process ends.

  In S108, engine ECU 300 determines whether or not the fuel injection amount transient increase stop condition is satisfied. Here, the transient increase stop condition is a condition that the engine 10 has completely exploded (the rotational speed of the engine 10 has become higher than a predetermined rotational speed). The transient increase stop condition is not limited to this.

  If the transient increase stop condition is satisfied (YES in S108), the process proceeds to S110. If not (NO in S108), the process proceeds to S112. In S110, engine ECU 300 stops the transient increase in the fuel injection amount. In S112, engine ECU 300 prohibits calculation (update) of the learning value.

  In S114, engine ECU 300 steadily increases the fuel injection amount in accordance with water temperature TW. For example, the fuel injection amount is increased as the water temperature TW is lower. In S116, engine ECU 300 permits the learning value to be calculated (updated).

  In S118, engine ECU 300 determines whether or not the steady increase stop condition for the fuel injection amount is satisfied. Here, the steady increase stop condition is a condition that the temperature of the engine 10, that is, the water temperature TW becomes higher than a predetermined temperature. Note that the steady increase stop condition is not limited to this, for example, a condition that a predetermined time has elapsed since the stop of the transient increase, or a rotation at which the cumulative number of rotations after the stop of the transient increase has been determined is predetermined. It may be a condition that the number is exceeded. If the steady increase stop condition is satisfied (YES in S118), the process proceeds to S120. If not (NO in S118), the process returns to S118.

  In S120, engine ECU 300 stops the steady increase of the fuel injection amount. Thereafter, this process ends.

  An operation of engine ECU 300 of the control device for an internal combustion engine according to the present embodiment based on the above-described structure and flowchart will be described.

  If a start request is detected from a state where engine 10 is stopped (YES in S100), as shown in FIG. 7, the engine is increased by transiently increasing the fuel injection amount in order to improve startability. 10 cranking is started and the engine 10 is started (S102).

  In this state, the air-fuel ratio is unstable and can change suddenly. Therefore, if the learning value is calculated during the transient increase, the learning value is erroneously calculated, and the fuel injection amount may be unnecessarily corrected.

  The learning value in the region of “DI ratio r = 100%” and the region of “0% <DI ratio r <100%” has an opportunity to be calculated after the engine 10 is warmed up. Since the opportunity to calculate the learning value in the region of “DI ratio r = 0%” is only during cold weather, it is necessary to calculate the learning value with higher accuracy.

  Therefore, when the engine is started, the coolant temperature TW is detected (S104), and it is determined whether the coolant temperature TW is lower than the threshold value TW (0) (S106). When cooling water temperature TW is lower than threshold value TW (0) (YES in S106), that is, when engine 10 is cold, it is determined whether or not the condition for stopping the transient increase in fuel injection is satisfied ( S108).

  When the fuel injection amount transient increase stop condition is not satisfied (NO in S108), that is, when the fuel injection amount transient increase is continued, calculation of the learning value is prohibited (S112). Thereby, it is possible to prevent the fuel injection amount from being unnecessarily corrected by calculating the learning value in a state where the air-fuel ratio can change suddenly.

  On the other hand, when the transient increase stop condition of the fuel injection amount is satisfied (YES in S108), that is, when the engine 10 has completely exploded, the transient increase of the fuel injection amount is stopped (S110). Here, as shown in FIG. 7, after the engine 10 has completely exploded at time T (1), the fuel injection amount is gradually decreased, and the transient increase of the fuel injection amount is stopped at time T (2). Suppose.

  Even after the transient increase is stopped, the fuel is difficult to vaporize in the cold state, and the normal engine fuel injection amount (the same fuel injection amount as the warm fuel injection amount) maintains the engine 10 speed at the desired speed. It may not be possible. Therefore, the fuel injection amount is steadily increased according to the water temperature TW (S114). Note that the operating state of the engine 10 at this time includes the idling time.

  If the fuel injection amount is constantly increased, it can be said that the air-fuel ratio is stable. Therefore, even if the learning value is calculated in this case, there is little possibility of being erroneously calculated. Further, the opportunity to calculate the learning value in the region of “DI ratio r = 0%”, that is, the learning value when fuel is injected only from the intake passage injection amount injector 120 is limited to the cold time. For this reason, even during cold weather, it is necessary to secure as many opportunities as possible to calculate the learning value and to accurately calculate the learning value in the region of “DI ratio r = 0%”.

  Therefore, in a state where the fuel injection amount is constantly increased according to the water temperature TW, calculation of the learning value is permitted (S116). As a result, the learning value is calculated in a state where the air-fuel ratio is stable. As shown in FIG. 8, the learning value is calculated for each learning region in each injection region (particularly, the region of “DI ratio r = 0%”). Obtainable. Further, although not shown, it is possible to obtain a learning value when “DI ratio r = 0%” during idling.

  FIG. 8 shows a state in which one learning value is calculated for each learning region in each injection region. Square points in FIG. 8 indicate learning values in the region of “DI ratio r = 100%”. Circle points indicate learning values in the region of “0% <DI ratio r <100%”. Triangular points indicate learning values in the region of “DI ratio r = 0%”.

  Thereafter, when the steady increase stop condition of the fuel injection amount is satisfied (YES in S118), that is, when the condition that the water temperature TW is higher than a predetermined temperature is satisfied, the steady increase of the fuel injection amount is Stopped (S120).

  As described above, according to the engine ECU of the control device for an internal combustion engine according to the present embodiment, when the engine is cold, when the fuel injection amount is transiently increased when the engine is started, Calculation of the learning value is prohibited. If the fuel injection amount is constantly increased according to the water temperature TW after the transient increase is stopped, the learning value is allowed to be calculated. Thereby, it is possible to suppress erroneous learning of the learning value in a state where the air-fuel ratio can change suddenly, and to calculate the learning value with high accuracy. Therefore, it is possible to prevent the fuel injection amount from being corrected unnecessarily. As a result, the air-fuel ratio can be controlled to an appropriate state, and the exhaust emission performance can be improved.

  For example, when the fuel injection amount is transiently corrected based on the fuel adhering to the wall surface of the intake port or the fuel purged from the canister (not shown), the air-fuel ratio becomes unstable. Therefore, the learning value calculated when such correction is performed during the period in which the fuel injection amount is constantly increased according to the water temperature TW is not stored in the RAM 330 and is based on this learning value. The correction of the fuel injection amount may be prohibited.

<Second Embodiment>
With reference to FIG. 9 and FIG. 10, a second embodiment of the present invention will be described. In the present embodiment, the DI ratio r is calculated using a map different from that of the first embodiment.

  Other structures and processing flow are the same as those in the first embodiment. The function about them is the same. Therefore, detailed description thereof will not be repeated here.

  With reference to FIG. 9 and FIG. 10, a map representing an injection ratio between in-cylinder injector 110 and intake passage injector 120 that is information corresponding to the operating state of engine 10 will be described. These maps are stored in the ROM 320 of the engine ECU 300. FIG. 9 is a map for the warm of the engine 10, and FIG. 10 is a map for the cold of the engine 10.

  9 and 10 differ from FIGS. 2 and 3 in the following points. The rotational speed of the engine 10 is “DI ratio r = 100%” in the region of NE (1) or more in the warm map and in the region of NE (3) or more in the cold map. In the region where the load factor is KL (2) or higher excluding the low rotational speed region in the warm map, and in the region where KL (4) is higher than the low rotational speed region in the cold map, “DI” Ratio r = 100% ”. This is because only the in-cylinder injector 110 is used in a predetermined high engine speed region, and only the in-cylinder injector 110 is used in a predetermined high engine load region. Indicates. However, in the high load region of the low engine speed region, mixing of the air-fuel mixture formed by the fuel injected from the in-cylinder injector 110 is not good, and the air-fuel mixture in the combustion chamber is inhomogeneous and combustion is unstable. Tend to be. For this reason, the injection ratio of the in-cylinder injector is increased with the shift to the high rotation speed region where such a problem does not occur. In addition, the injection ratio of the in-cylinder injector 110 is decreased as the engine shifts to a high load region where such a problem occurs. These changes in the DI ratio r are shown by cross arrows in FIGS. If it does in this way, the fluctuation | variation of the output torque of an engine resulting from combustion being unstable can be suppressed. It should be noted that these things can be achieved by reducing the injection ratio of the in-cylinder injector 110 as the engine shifts to the predetermined low rotational speed region, or by the in-cylinder injection as the vehicle shifts to the predetermined low load region. The fact that it is substantially equivalent to increasing the injection ratio of the injector 110 for operation will be described. Further, areas other than such areas (areas where the cross arrows are shown in FIGS. 9 and 10) and areas where fuel is injected only by the in-cylinder injector 110 (high rotation side, low load) On the other hand, it is easy to homogenize the air-fuel mixture with the in-cylinder injector 110 alone. Thus, the fuel injected from the in-cylinder injector 110 is vaporized with latent heat of vaporization (sucking heat from the combustion chamber) in the combustion chamber. Thereby, the temperature of the air-fuel mixture at the compression end is lowered. As a result, the knocking performance is improved. Further, since the temperature of the combustion chamber is lowered, the suction efficiency is improved and high output can be expected.

  In the engine 10 described in the first and second embodiments, the homogeneous combustion is performed by setting the fuel injection timing of the in-cylinder injector 110 as the intake stroke, and the stratified combustion is performed by the in-cylinder injector 110. This can be realized by setting the fuel injection timing in the compression stroke. That is, by setting the fuel injection timing of the in-cylinder injector 110 as the compression stroke, stratified combustion is realized in which the rich air-fuel mixture is unevenly distributed around the spark plug and the entire combustion chamber ignites a lean air-fuel mixture. Can do. Further, even when the fuel injection timing of the in-cylinder injector 110 is set to the intake stroke, if rich air-fuel mixture can be unevenly distributed around the spark plug, stratified combustion can be realized even with the intake stroke injection.

  Further, the stratified combustion here includes both stratified combustion and weakly stratified combustion described below. In the weak stratified combustion, the intake passage injector 120 is injected with fuel in the intake stroke to produce a lean and homogeneous mixture in the entire combustion chamber, and the in-cylinder injector 110 is injected with fuel in the compression stroke. A rich air-fuel mixture is generated around the spark plug to improve the combustion state. Such weak stratified combustion is preferable when the catalyst is warmed up. This is due to the following reason. That is, it is necessary to significantly retard the ignition timing and maintain a good combustion state (idle state) in order to allow high-temperature combustion gas to reach the catalyst during catalyst warm-up. Moreover, it is necessary to supply a certain amount of fuel. Even if this is done by stratified combustion, there is a problem that the amount of fuel is small, and even if this is done by homogeneous combustion, there is a problem that the retard amount is small compared to stratified combustion in order to maintain good combustion. is there. From such a viewpoint, it is preferable to use the above-described weak stratified combustion at the time of warming up the catalyst, but either stratified combustion or weak stratified combustion may be used.

  In the engine described in the first and second embodiments, the timing of fuel injection by the in-cylinder injector 110 is preferably performed in the compression stroke for the following reason. However, in the engine 10 described above, in a basic most region (a weak operation that is performed only when the catalyst is warmed up, the intake passage injection injector 120 is injected in the intake stroke and the in-cylinder injector 110 is compressed in the compression stroke. The timing of fuel injection by the in-cylinder injector 110 other than the stratified combustion region is a basic region) is the intake stroke. However, for the following reasons, the fuel injection timing of the in-cylinder injector 110 may be temporarily set to the compression stroke injection for the purpose of stabilizing the combustion.

  By setting the fuel injection timing from the in-cylinder injector 110 during the compression stroke, the air-fuel mixture is cooled by fuel injection at a time when the in-cylinder temperature is higher. Since the cooling effect is enhanced, knock resistance can be improved. Furthermore, if the fuel injection timing from the in-cylinder injector 110 is in the compression stroke, the time from the fuel injection to the ignition timing is short, so that the air flow can be strengthened by spraying and the combustion speed can be increased. From these improvement in knocking property and increase in combustion speed, combustion fluctuation can be avoided and combustion stability can be improved.

  Furthermore, regardless of the temperature of the engine 10 (that is, whether the engine is warm or cold), it is off-idle (when the idle switch is off or the accelerator pedal is depressed). 2 or 9 may be used (the in-cylinder injector 110 is used in the low load region regardless of the cold temperature).

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of the engine system controlled by the control apparatus which concerns on the 1st Embodiment of this invention. It is a figure showing DI ratio map at the time of warm memorized by engine ECU which is a control device concerning a 1st embodiment of the present invention. It is a figure showing the DI ratio map at the time of cold memorized by engine ECU which is a control device concerning a 1st embodiment of the present invention. It is FIG. (1) which shows the learning area | region of the fuel injection quantity memorize | stored in engine ECU which is a control apparatus which concerns on the 1st Embodiment of this invention. FIG. 8 is a diagram (No. 2) illustrating a fuel injection amount learning region stored in the engine ECU that is the control device according to the first embodiment of the present invention. It is a flowchart which shows the control structure of the program which engine ECU which is a control apparatus which concerns on the 1st Embodiment of this invention performs. It is a timing chart which shows transition of fuel injection quantity. It is a figure which shows the state by which the learning value was calculated for every learning area | region about each injection area | region. It is a figure showing the DI ratio map at the time of warm memorize | stored in engine ECU which is a control apparatus which concerns on the 2nd Embodiment of this invention. It is a figure showing DI ratio map at the time of cold memorized by engine ECU which is a control device concerning a 2nd embodiment of the present invention.

Explanation of symbols

  10 engine, 20 intake manifold, 30 surge tank, 40 air intake duct, 42 air flow meter, 50 air cleaner, 60 electric motor, 70 throttle valve, 80 exhaust manifold, 90 three-way catalytic converter, 100 accelerator pedal, 110 in-cylinder injector , 112 cylinder, 120 Injector injector, 130 Fuel distribution pipe, 140 Check valve, 150 High pressure fuel pump, 152 Electromagnetic spill valve, 160 Fuel distribution pipe (low pressure side), 170 Fuel pressure regulator, 180 Low pressure fuel pump, 190 fuel filter, 200 fuel tank, 300 engine ECU, 310 bidirectional bus, 320 ROM, 330 RAM, 340 CPU, 350 input port, 360 output port, 370, 39 , 410,430,450 A / D converter, 380 a water temperature sensor, 400 a fuel pressure sensor, 420 an air-fuel ratio sensor, 440 an accelerator opening sensor, 460 rpm sensor.

Claims (4)

A control device for an internal combustion engine comprising a first fuel injection means for injecting fuel into a cylinder and a second fuel injection means for injecting fuel into an intake passage,
At least at the time of cranking and idling when the temperature of the internal combustion engine is equal to or lower than a predetermined value , fuel is injected from only one of the first fuel injection means and the second fuel injection means. First control means for controlling the fuel injection means;
Second control means for controlling the fuel injection means such that fuel is injected from the first fuel injection means and the second fuel injection means;
First calculation means for calculating a feedback correction value of the fuel injection amount based on the air-fuel ratio;
A second calculating means for calculating a learning value of the feedback correction amount when a predetermined condition is satisfied;
Prohibiting means for prohibiting calculation of the learning value at least during a period from the start of cranking of the internal combustion engine to a complete explosion;
Control means for permitting calculation of the learned value during a period in which the fuel injection amount is corrected based on the temperature of the internal combustion engine when the internal combustion engine is idle after a complete explosion apparatus.   The first control means is configured to cause the fuel injection means to inject fuel only from the second fuel injection means when cranking or idling when the temperature of the internal combustion engine is equal to or lower than a predetermined value. The control apparatus for an internal combustion engine according to claim 1, comprising means for controlling the engine. The control device is configured to control the fuel injection amount based on a value other than the temperature and air-fuel ratio of the internal combustion engine during a period in which the fuel injection amount is corrected based on the temperature of the internal combustion engine when the internal combustion engine is idle after a complete explosion. The control apparatus for an internal combustion engine according to claim 2, further comprising means for prohibiting correction of the fuel injection amount based on the correction value calculated when the correction is made. The first fuel injection means is an in-cylinder injector,
The control device for an internal combustion engine according to any one of claims 1 to 3, wherein the second fuel injection means is an intake passage injector.

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